Various catalyst systems have been employed to produce high trans-1,4-polybutadienes. Certain catalyst systems have been used to produce high trans-1,4-polybutadiene having two distinct melting points. U.S. Pat. No. 5,174,838, to Sandstrom et al, discloses a cobalt based catalyst to produce a trans 1,4-polybutadiene rubber having 75% to 85% of trans 1,4-content, 12% to 18% of 1,2-content, 3% to about 8% of cis 1,4-content and, in its uncured state, having a major melting point in a range of about 35.degree. C. to about 45.degree. C. and a second minor melting point in the range of about 55.degree. C. to about 65.degree. C. U.S. Pat. No. 5,037,912, to Patterson et al, discloses an organolithium and alkali metal alkoxide catalyst in a process for synthesizing trans 1,4-polybutadiene having a trans isomer content of about 80% to about 90% and two distinct melting points, namely a first melting point of about 60.degree. C. to about 80.degree. C. and a second melting point of about 135.degree. C. to about 155.degree. C.
High trans polybutadienes have been used as rubber additive such as in Japan Patent Application Publication No. Hei 3-65828 displaying the blends of 3 to 20 parts by weight of a high trans 1,4-polybutadiene having 75% to 90% of trans 1,4-content and 3% to 10% of vinyl linkages and 97 to 80 parts by weight of a diene-type rubber.